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Biomedical subjects

M L Silva

Publications and source records attributed to M L Silva.

At least 37 records · Page 2Linked to original sources

Early clinical and EEG features of infantile spasms in Down syndrome.

The combination of West syndrome (WS) and Down syndrome appears not to be coincidental. Fourteen patients free of cardiac malformation or history of perinatal hypoxia were referred and investigated before they had received any treatment and were followed to the mean age of 4.5 years (range 19 months to 14 years). Spasms had onset at the mean age of 8 months (range 4-18 months) in cluster and were symmetrical. Hypsarrhythmia was symmetrical and, after intravenous diazepam (4 patients, 0.5 mg/kg) it disappeared, without any remaining focus. Recorded spasms during a cluster were "independent," with recurrence of hypsarrhythmia between successive spasms, and thus had the ictal and interictal EEG characteristics of idiopathic WS. Seven patients exhibited other types of seizures after WS, consisting of myoclonic jerks, atonic, tonic-clonic or absence seizures, which proved quite easy to control with valproate and/or ethosuximide.

Adolescent↗

Antigenic components of partially purified antigens of Leishmania donovani infantum recognized by sera from dogs with asymptomatic or active visceral leishmaniasis.

The antigenic components of a semipurified fraction of Leishmania donovani infantum were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis using 14 serum samples from dogs with symptomatic visceral leishmaniasis and 11 serum samples from apparently healthy dogs collected in an area endemic for canine visceral leishmaniasis (CVL). It was found that these antigens were composed of many polypeptides, among which seven components recognized by symptomatic CVL sera, had molecular weights of approximately 18, 28, 30, 33, 63, 70, and 72 kilodaltons (kD); two components of 63 and 70 kD were recognized by three of 11 healthly dog sera. These findings suggest that specific antigens induce humoral immune response in dogs with asymptomatic or active visceral leishmaniasis. Infected dogs are not readily identifiable by their symptoms. The potential interest of the immunoblot test for CVL diagnostic purposes is discussed.

Animals↗

An in vitro model to study the effect of antibodies and cell receptor analogues on meningococcal adherence to human oroepithelial cells.

We have investigated different experimental schedules to achieve adherence of Neisseria meningitidis group B to cultured and buccal epithelial cells (BEC) and the effect of antibodies and receptor analogues on bacterial adherence. No adherence of meningococcus was observed when HeLa, HEp-2 or KB cells were used, but high rates of adherence to BEC occurred. The effect of antibodies on bacterial adherence was studied in assays carried out in the presence of saliva and serum collected from convalescing children with meningococcal meningitis and children vaccinated with VAMENGOC B-C. Both saliva and serum from the convalescent patients inhibited the adherence of meningococci, but saliva and serum from vaccinated children did not, corroborating our previous data of a poor antibody response induced by this vaccine. Human colostrum did not affect meningococcal adherence despite the presence of antibodies to N. meningitidis detected by ELISA. Inhibition of adherence by sera from an immunized horse, rabbits and mice, as well as by cell receptor analogues (outer-membrane complex and purified polysaccharide C), was observed. Our results show that up to now BEC continue to be the best cells to study meningococcal adherence and the effect of adherence inhibitors.

Antibodies, Bacterial↗

Effect of microwave radiation, pasteurization and lyophilization on the ability of human milk to inhibit Escherichia coli adherence to HEp-2 cells.

The effect of different physical treatments on the ability of colostrum and human milk to inhibit the adherence of enteropathogenic Escherichia coli (EPEC) to human epithelial cells was studied. Pools of colostrum and milk were submitted to microwave radiation, pasteurization or lyophilization, and then tested for the ability to inhibit the adherence of EPEC O111:H- to HEp-2 cells. The inhibitory effect of untreated colostrum and human milk on localized adherence was not significantly modified after exposure to any treatment. The total protein values of colostrum and milk were maintained, but IgA concentration and colostral anti-EPEC IgA were reduced after pasteurization. Nevertheless, the remaining IgA was sufficient to be effective in adhesion inhibition assay. Western blotting assays carried out with EPEC antigens showed that the treated and untreated pools recognize a 94-kDa outer-membrane protein which molecular weight is compatible with intimin, an EPEC adhesin related to bacterial attachment to epithelial cells. These results suggest that the protection of colostrum and milk to infantile diarrhoea due to EPEC remains unalterable after the physical treatments studied.

Adhesins, Bacterial↗

Translocation 11;14 in three children with acute lymphoblastic leukemia of T-cell origin.

Clinical, karyotypic, immunophenotypic, and molecular profiles of three TALL cases carrying a t(11;14) are discussed and compared with data in the literature. As previously reported, t(11;14)(p13;q11) was associated in one patient with a TALL profile of intermediate stage of maturation (CD7+, CD4+, CD8+). However, the same translocation was found to be present in another patient with a more immature, pro-TALL profile (CD7+, CD4-, CD8-). Both patients showed molecular rearrangements of the TCR beta chain gene. A third patient, with a very immature pro-TALL profile (CD34+, CD7+, CD4-, CD8-), carrying a t(11;14)(p15;q11), showed molecular rearrangements of the TCR beta and gamma chain genes, while the IgH chain genes were in germline configuration. Our data indicate that t(11;14) can also be present in TALLs of more immature stages of intrathymic development; the significant factor determining the clinical behavior of TALLs is apparently related more to cell differentiation than to the presence of this chromosome rearrangement.

Adolescent↗

Prenatal ultrasonographic diagnosis of ductus arteriosus aneurysm with spontaneous neonatal closure.

Aneurysm of the ductus arteriosus may be either spontaneous or acquired as a complication of surgical closure of a patent duct. Patients may be asymptomatic or present with a wide spectrum of symptoms, including hoarseness, respiratory symptoms, aortic or pulmonary thrombosis or embolism, or rupture of the aneurysm. We present the first report of prenatal ultrasonographic diagnosis of isolated ductus arteriosus aneurysm. The aneurysm presented at 39 weeks as an enlarged, dilated, vascular structure 15 mm in diameter, which began at the bifurcation of the main pulmonary artery and ended in the descending aorta. Doppler imaging demonstrated turbulent flow in this lesion. Following spontaneous delivery, a bidirectional shunt in the ductus arteriosus was found on the 1st day, but the caliber of the vessel was normal. An almost completely functionally closed ductus was found on the 2nd day. Spontaneous resolution of the lesion was confirmed by magnetic resonance imaging at 4 weeks of age.

Adult↗

The antimeningococcal vaccine VAMENGOC B-C induced poor serum and salivary antibody response in young Brazilian children.

In 1989 about 2.3 million Brazilian children received the antimeningococcal vaccine VAMENGOC B-C (Havana, Cuba). We evaluated the serum and secretory immune response of vaccinated children by enzyme-linked immunosorbent assay with outer membrane complex antigens. Western blotting and bacterial adherence inhibition assays with human buccal epithelial cells were performed with some of the samples. Serum and salivary antibody concentrations to Neisseria meningitidis Group B of vaccinated children < 4 years old were not significantly higher than those of nonvaccinated children, as observed in convalescing patients used as positive controls. Older children (4 to 6 years old) presented a slight increase in antibody OD indexes. Sera and saliva from vaccinated children showed a weak reaction with meningococcal antigen by Western blotting and were unable to inhibit significantly the adherence of N. meningitidis B to buccal epithelial cells. These data suggest that this vaccine induced a poor serum and salivary antibody response in the population studied.

Antibodies, Bacterial↗

Inhibition of HEp-2 cell invasion by enteroinvasive Escherichia coli by human colostrum IgA.

This paper demonstrates that human colostrum can inhibit the invasion of HEp-2 cells by enteroinvasive Escherichia coli (EIEC) of serotypes O28:H- and O29:H-, and that IgA antibodies mediate the inhibitory process. Seventy three of 77 (95.9%) colostrum samples prevented invasion of HEp-2 cells by E. coli O28:H-. Most of these samples contained high levels of IgA reactive to EIEC in immunoenzymatic assays. IgA eluted from an affinity chromatography column strongly inhibited HEp-2 invasion by EIEC, whereas IgA-depleted colostrum had no inhibitory effect on bacterial invasion. Immunoblots of colostrum samples with high (> 60%) invasion-inhibiting levels were performed with water extracts of invasive and noninvasive strains. Bacterial antigens from the invasive strain were recognized and the size of some was consistent with the invasion plasmid antigens (Ipas) A, B, C, and D, with stronger reactions with Ipas A and C. Colostrum samples with high inhibitory levels showed a strong reaction in Western blot assays, in contrast to the faint bands observed with poor-inhibitory samples. The results obtained in the present study suggest that colostrum IgA may protect infants against invasive E. coli infections.

Antibodies, Bacterial↗

Inhibition of enteropathogenic Escherichia coli adhesion to HeLa cells by serum of infants with diarrhea and by cord serum.

We have studied the effect of serum from infants with diarrhea and of cord serum on the localized adherence of enteropathogenic Escherichia coli (EPEC) to HeLa cells. Serum samples from 16 infants with diarrhea due to EPEC of serotypes O55:H6, O111: H-, O111:H2, O119:H6 and O142:H6 were used. The adherence ability of EPEC strains belonging to serotypes identical to (homologous) or different from (heterologous) those isolated from the infants' feces was highly inhibited by samples of infant serum collected both during the acute phase of the illness and upon discharge from the hospital. These data confirm the development of antibodies against EPEC adhesins and the cross-reaction between different EPEC serotypes. Cord serum inhibited the localized adherence of EPEC strains at different levels according to the serotype of the strain studied. These results suggest that the placental transfer of adhesin-related antibodies does not protect the newborn against EPEC infections, since half of our patients were less than 30 days old.

Bacterial Adhesion↗

Immunological recovery after bone marrow transplantation for severe aplastic anaemia: a Brazilian experience.

Twenty-nine patients with severe aplastic anaemia (SAA) were submitted to bone marrow transplantation (BMT) and their immunological recovery analysed. Total lymphocyte counts, estimation of B lymphocytes, T lymphocytes and their subsets, natural-killer (NK) activity were performed. Cells with the CD8+ phenotype and NK activity were the first signs of immunological recovery, whereas the CD4+ subset recovered later in patients who suffered from acute graft versus host disease (GvHD) and infections. Acute and chronic GvHD, cirrhosis, rejection and HIV viral infection contributed to the persistence of the profound immunodeficiency status observed after BMT. Our results did not differ greatly from the others and confirmed that BMT may be performed in underdeveloped countries despite the difficulties it might pose.

Adult↗

Inhibition of enteropathogenic Escherichia coli (EPEC) adhesion to HeLa cells by human colostrum: detection of specific sIgA related to EPEC outer-membrane proteins.

Human colostrum and a high molecular weight colostrum fraction (HMWF; > 14,000 D) prevented the adhesion of localized adherent (LA+) O111:H-enteropathogenic Escherichia coli (EPEC) to HeLa cells. This effect was abolished after absorption with an O111:H-LA + EPEC strain, but absorption with a LA- strain of same serotype had no effect on the process. A low molecular weight fraction (< 14,000 D), absorbed or not with LA+ or LA- bacterial strains, did not inhibit the adherence of E. coli to HeLa cells. IgA-depleted colostrum had no inhibitory effect on bacterial adhesion, demonstrating the critical role of this protein in the phenomenon. Heat inactivation of whole colostrum did not significantly modify the inhibition adherence levels. Immunoblots of O111:H-LA+ strain outer-membrane complex reacted with colostrum and HMWF showing that IgA antibodies were predominantly reactive with a 94-kD protein. These data confirm and extend observations about colostrum sIgA participation in adhesion inhibition of EPEC to HeLa cells and its response to a 94-kD outer-membrane protein.

Bacterial Adhesion↗

Translocation of CD3D gene in an acute myeloid leukemia (M5) with t(11;17)(q23;21).

Cytogenetic studies in patients with acute leukemia showed structural abnormalities on chromosome 11 at band q23 in five cases. Four of these had acute lymphoblastic leukemia (ALL) associated with t(4;11)(q21;q23) and one case had acute nonlymphoblastic leukemia (ANLL) (M5) associated with t(11;17)(q23;q21). We examined the CD3D and c-ets-1 genes in the t(11;17)(q23;q21) patient to ascertain any association between them and the chromosome change. In situ hybridization results showed that unlike in other studied cases with rearrangements of 11q23, the CD3D gene in the t(11;17)(q23;21) is transposed to the der(17) chromosome, providing evidence for a different breakpoint in the 11q23 region.

CD3 Complex↗

Acute megakaryoblastic leukemia in children and adolescents: a retrospective analysis of 24 cases.

In order to characterize the clinical, cytogenetic, and outcome features of childhood acute megakaryoblastic leukemia (AMKL), we reviewed 24 cases; 14 were identified among 150 consecutive newly diagnosed acute myelogenous leukemia (AML) patients at St. Jude Children's Research Hospital, and 10 were cases referred to the National Institute of Cancer in Rio de Janeiro, Brazil. There were 5 Down syndrome patients and one patient with chronic myeloid leukemia (Ph+) in blastic crisis. Twelve patients had significant hepatosplenomegaly. Leukemic cell morphology and cytochemistry were consistent with the M7 classification in 17 cases, and all cases tested expressed megakaryocytic surface antigens. AMKL patients were significantly younger than other AML patients (P = 0.0001) and had poorer responses to therapy (P = 0.03, univariate analysis only). Ten of 24 failed induction, and only 5 are disease-free at 6 months to 4.5+ years. We conclude that AMKL usually affects young children, frequently producing marked organomegaly. It comprises approximately 10% of pediatric AML cases, and responds poorly to intensive AML therapies.

Adolescent↗

Oral ciprofloxacin for treatment of chronic osteomyelitis.

Seventeen adult patients with chronic osteomyelitis were treated with oral ciprofloxacin, 750 mg twice daily. Treatment ranged from 28 to 254 days. Efficacy was considered to be good, based upon clinical resolution observed in 13 patients (76%). Clinical and microbiological failure was observed in 3 patients (18%), and there was one case of reinfection. Tolerance was very satisfactory, since the adverse reactions were mild and transitory; these occurred in 7 patients (41%), being cutaneous rash in 4 patients and diarrhoea in 3 patients. No patient had to discontinue treatment. Thus, oral ciprofloxacin may be useful option for the prolonged treatment of chronic osteomyelitis, provided that it is always associated with surgical debridement. Due to the probable development of ciprofloxacin resistance in the S. aureus multiresistant strain, already observed in two patients in the present investigation, it is suggested that for the treatment of such infections another drug with antistaphylococcal activity should be associated with the ciprofloxacin.

Administration, Oral↗